The present invention relates to one-way clutch systems permitting, for example, a driven member to be positively driven by a driving member in one direction only, being capable of free-wheeling or over-run relative to the driving member when not in driven engagement with the driving member.
One-way clutches hereto known in the prior art are generally of the frictional drive type. They consist of a number of rollers or sprags disposed between an outer and an inner race, which are wedged between the surfaces of the inner and outer races for causing one or the other of the races to drive the other. When the driven race over-runs the driving race or when the driving race rotates in an opposite direction, the rollers or sprags are no longer caused to be wedged between the races, and the races are relatively free to rotate relative to each other. However, as the rollers or sprags are spring-loaded towards engagement, even during free-wheeling or over-running, a portion of the surface of the rollers or sprags contacts the surface of both the inner and outer races, thus causing friction resulting in drag, and therefore heat, and wear of the surfaces in contact. Frictional one-way clutches have therefore inherent limitations in torque transmittal capacities, which depend on the frictional effect of the surfaces in contact, in life, due to wear, and in the permissible relative speeds of rotation during free-wheeling and over-run.
Other types of one-way clutches, known as one-way ratchet clutches, consist of, in one version, spring-biased ratchet members pivotally attached to a clutch member at one end and provided at their other end with a hook-like portion engageable with the bearing face of a tooth-like ring fastened to the other clutch member. When the two clutch members tend to rotate in driving directions, the hook-like end of the ratchets engages the bearing surfaces of the teech thus causing the other clutch member to rotate in unison. When the relative rotation of the driving clutch member is in an opposite direction, that is during free-wheeling or over-run, the hook-like end of the ratchets is permitted by the spring to ride over each tooth of the toothed ring, as an escapement mechanism, permitting relative rotation of the members. Such ratchet-type one-way clutches are noisy, they are limited in their torque transmitting capacity, and they are subject to important wear in view of the ratchet ends continuously rubbing against the toothed member during over-running or free-wheeling.
Another type of ratchet one-way clutch consists generally of a pair of disk members provided with engageable faces having teeth, one side of which forms an inclined plane and the other side of which forms an abutment in the plane approximately parallel to the axis of rotation of the disk members. One disk member is constantly biased by spring pressure towards the other disk member. When the direction of rotation of the driving member causes the corresponding faces of the teeth in a plane parallel to the axis of rotation to engage, the driving member drives the driven member. When the driven member over-runs the driving member or the driving member runs oppositely the teeth inclined side engages and rides over each other, thus laterally displacing one of the disks against the spring pressure. Such one-way ratchet clutches are inherently subject to extreme wear, due to the spring pressure, and are subject, for the same reason, to considerable drag force during free-wheeling or over-running, and they generate considerable heat, and are limited in over-run or free wheeling speeds.